1. Field of the Invention
This invention relates to a light coupled semiconductor device which comprises a light emitting semiconductor element and a light sensing semiconductor element optically and integrally coupled with the light emitting semiconductor element and to a method for manufacturing the same.
2. Description of the Prior Art
Hitherto, this type of light coupled semiconductor device has been known as a photo-coupler. A photo-coupler which affords a signal transmission between its input and output sides which are electrically insulated from each other is being widely used especially for transmitting signals between circuits at different potentials or for effecting high-power controlling through the use of weak signals.
A prior art light coupled semiconductor device is disclosed in U.S. Pat. No. 3,535,532 issued on Patent Application Ser. No. 820,037 filed Apr. 21, 1969 by the name of Jerry D. Merryman, assigned to Texas Instruments Inc. and entitled to "Integrated Circuit including Light Source, Photodiode and associated Components". The prior art device comprises a light emitting semiconductor element and a light sensing semiconductor element with their principal surfaces being arranged oppositely on which the light emitting area and light sensing area are provided respectively, and a light guide made of glass for optically coupling the light emitting area to the light sensing area. This prior art light coupled semiconductor device, however, is disadvantageous in that although the light emitting area and the light sensing area occupy only a part of the respective principal surface, the light guide is held in contact at their respective ends with the principal surfaces to cover not only the portions where the light emitting and sensing areas are provided, but also the peripheral portions thereof and as a result, the optical coupling efficiency is considerably degraded.